The present invention relates to a polishing composition mainly used in the application of polishing silicon oxide materials, more specifically in the application of polishing glass substrates for hard disks, synthetic quartz substrates for photomasks, or low-dielectric-constant films such as silicon dioxide films, borophosphosilicate glass (BPSG) films, phosphosilicate glass (PSG) films, fluorosilicate glass (FSG) films, and organosiloxane films of semiconductor devices. The present invention also relates to a polishing method using the above composition.
To improve the quality of silicon oxide materials after polishing, polishing compositions used in the application of polishing silicon oxide materials are strongly required to reduce, by polishing, the surface roughness and the number of surface defects such as scratches on silicon oxide materials. Furthermore, in order to decrease the time required for the polishing work, the polishing composition is also required to provide a high polishing rate (removal rate) of the silicon oxide materials.
As a polishing composition that can be used in the application of polishing silicon oxide materials, polishing compositions described, for example, in Patent Documents 1 to 4 are conventionally known. The polishing composition of Patent Document 1 contains abrasive grains such as colloidal silica and a polymer having a sulfonic group such as an acrylic acid/sulfonic acid copolymer. The polishing composition of Patent Document 2 contains abrasive grains such as colloidal silica and a zeta potential regulator comprising an acid, a base, a salt, or a surfactant for regulating the zeta potential of the abrasive grains in the range of −15 to 40 mV. The polishing composition of Patent Document 3 contains colloidal silica having an average primary particle size of 60 nm or less and has a pH adjusted in the range of 0.5 to 4. The polishing composition of Patent Document 4 contains colloidal silica having a degree of association of more than 1 and an acid and has a pH adjusted in the range of 1 to 4. However, these conventional polishing compositions are unsatisfactory for sufficiently satisfying all the above-described requirements and still have room for improvement.